1/14/02 UCSD 1 UBC software modularity group

basis of crosscutting

• a join point model (JPM) has 3 critical elements– what are the join points

• in AspectJ– points in runtime call graph– class members

– means of identifying join points• in AspectJ

– signatures (plus …)– means of specifying semantics at join points

• in AspectJ– advice– define members

1/14/02 UCSD 2 UBC software modularity group

basis of crosscutting

• a join point model (JPM) has 3 critical elements– what are the join points

• in AspectJ– points in runtime call graph– class members

– means of identifying join points• in AspectJ

– pointcuts– member signatures (plus …)

– means of specifying semantics at join points• in AspectJ

– advice– define members

dynamic JPMstatic JPM

1/14/02 UCSD 3 UBC software modularity group

range of AOP languages

means of … join points

JPM join points identifying specifying semantics at

AspectJ dynamic JPM

points in execution call, get, set…

signaturesw/ wildcards & other properties of JPs

advice

static JPM class members signatures add members

Composition Filters message sends & receptions

signature & property based object queries

wrappers declarative (filters) imperative (advice)

Hyper/J members signatures add, compose (and remove) members

Demeter traversals when traversal reaches object or edge

class & edge names

define visit method

See next slide for changes to

AspectJ and Demeter

1/14/02 UCSD 4 UBC software modularity group

range of AOP languages

means of … join points

JPM join points identifying specifying semantics at

AspectJ dynamic JPM

points in execution call, get, set…

signaturesw/ wildcards & other properties of JPs

advice

static JPM classes class names add members

Demeter

static JPM 1

static JPM 2

when traversal reaches object or edge

classes

classes

visitor method signatures

traversal spec. sclass graph g

class names

visitor method bodies

add traversal membersbased on s,g

add members

1/14/02 UCSD 5 UBC software modularity group

Composing join point models

• Traversal Spec JPM: In Demeter we use traversal specifications and the class graph to introduce traversal methods to a set of classes.

• Visitor JPM: The result of Traversal Spec. JPM is used to define a second JPM: – The traversal methods define nodes and edge visits. – Visitor signatures define the nodes and edges where

additional advice is needed: they are the means of identifying join points.

– The means of specifying semantics at join points are the visitor bodies.

1/14/02 UCSD 6 UBC software modularity group

• foo– dynamic JPM (~ AspectJ)– what happens in pattern

• bar

AO design in UML

• Composition Patterns– static JPM (~ Hyper/J)– binds pattern to base code

• UML class & interaction diagrams already crosscut– by-class vs. by-interaction organizations

[Clarke, Walker]